Crankin dat soulja boy

Although widely known as a dance from 2007 created by Soulja Boy Tellem, the phrase also refers to male masturbation. The reason it is known as such is because the penis is similar to a solider with its helmet, and it is cranked like a crankshaft during masturbation.

"I walked in on dat nigga, and he was Crankin dat soulja boy, so I dipped."